http://www.webpagetest.org/result/110314_KT_5AHD/1/pagespeed/ makes these key recommendations:
- Leverage browser caching
- Parallelize downloads across hostnames
- Enable compression
- Combine images into CSS sprites
- Minify CSS
The first three are server-side changes, the latter-two can be done by Web Services.
See Webserver config change requests.
For the minification and concatenation of CSS and JS we could look at http://code.google.com/p/minify/ as tool to get us started.
Google's online Page Speed tool gives these results
Additionally there are other standard practices we should be following:
- optimize images
- Late loading of resources where not immediately necessary (images/HTML that are off-screen or accessible via JS, images/JS/HTML loaded later in the document where not immediately needed) - for example, work from China page loading time can be seen here - click on Agent Location.
- Reduce the number of requests where possible (CSS sprites, concatenate CSS and JS)
Liam has also pointed out images may not be correctly compressed and looking at http://www.webpagetest.org/result/101101_A72Y/1/performance_optimization/#compress_images it indicates a saving of 309.8 KB.
We have not yet looked at optimising our HTTPS serving. There is a resource here http://blog.httpwatch.com/2009/01/15/https-performance-tuning/ which appears useful.